Mythbusters "tests" efficiency of dimples vs. smooth, and clean vs. muddy car
 

Admin note: 2 threads were started on this topic. The other one is here: http://ecomodder.com/forum/showthrea...les-10718.html

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I don't watch the show regularly, but this one might be worth tuning in for the entertainment factor.

Also.. don't they have it backward? Isn't the common myth that the clean car gets better mileage?

Hmm, I can imagine having enough mud buildup in the wheelwells to reduce the distance between them and the wheels. Or mud sticking to the rear of the car, drying and hardening, layer on layer, in the shape of a Kammback extension. But by the time either of these would have a noticeable aero effect, the weight penalty would start to be a pain.

I will be watching it. I love mythbusters even tho they seem to be obsesed with explosions.

I love Mythbusters BECAUSE they seem to be obsesed with explosions... hehehee

I think the muddy/clean thing is like the golfball dimple theory. Sometimes rough is better than smooth. I'm actually looking forward to this one...

If it works you could cover your car with rocker guard or ceiling texture and paint over it. Might look kind of cool.

They are supposed to be "dimpling" a car, I think.

I could just see them firing golf balls at a car to get the dimples.

SOunds like a hail storm car to me! :)

Dave

I'm sure it'll be entertaining and worth watching.

I predict their conclusion will be "we can not detect a fuel economy difference between these two cars".

It would take a pretty extreme setup to do aerodynamic testing sensitive enough to detect mud. A wind tunnel would do it, but they wouldn't take a car to a wind tunnel for a simple myth like this. Short of that, you'd need high speed bidirectional coastdown testing on a totally windless day. Even if you accounted for airspeed, small crosswinds would skew your results beyond utility.

As to the effects of mud: It tends to increase the car's frontal area, obviously. Cakes of mud on streamlined surfaces will increase your Cd, while cakes of mud in your eddies will tend to decrease your Cd. A muddy truck with its panel gaps and hood cowl filled with mud will probably get better gas mileage, but unless your aeromodded Metro gets a teardrop-shaped tail made of mud, it's likely to get slightly worse gas mileage when muddy.

New myth - it stems from the golf ball conundrum.

I can't imagine what type of thoughtless people frequent the MB forums to come up with/perpetuate this ****.